1. Field of the Invention
The present invention generally relates to multiple-processor systems, and more particularly, to a packet switch, having multiple processing engines, for transferring information between hosts in a network environment.
2. Related Art
Packet switches are devices that are commonly found in networks. In general, a network packet switch takes ingress packet traffic, classifies such traffic, performs rewrites of packet header and data information, and then forwards that traffic to another device or host on the network.
The operation of packet switches can be described using layered protocol models. As is well known, most networked computer communication is defined with the aid of layered reference models for depicting the movement of information between host computers connected to the network. The layers in the reference models help to segregate information and network functions into manageable units. The general functions of each layer are often based on an international standard called Open System Interconnection (OSI). OSI sets forth seven processing layers through which information may pass when received by a host in order to be presentable to a non-user. Similarly, transmission of information from a host to the network may pass through those seven processing layers in reverse order. Another layered reference model that is widely implemented is called TCP/IP (Transmission Control Protocol/Internet Protocol).
To improve the performance of a network switch, a multi-processor architecture can be employed to carry out the networking functions of the switch. In such an architecture, switch functionality is distributed among multiple processing engines, which operate on packet traffic in a parallel or pipelined fashion. This generally improves the overall throughput and performance of the switch. However, in this processing arrangement, there needs to be a mechanism for coordinating the operations of the processing engines so that shared resources are efficiently used and temporal consistency is maintained for packets moving through the switch.